Halley's Comet is one of the most famous comets and has a periodic orbit that brings it close to Earth approximately once every 76 years. When it does make an appearance, it remains visible for several weeks or even a couple of months, depending on various factors.
The visibility of a comet like Halley's depends on its distance from the Earth, its brightness, and the conditions for observation (such as light pollution and weather). Typically, Halley's Comet is visible to the naked eye for a few weeks as it approaches Earth, reaches its closest point (perihelion), and then moves away.
During its closest approach, the comet may be visible in the night sky for several hours each night. However, the visibility can vary, and it is generally more easily observed in the pre-dawn or post-sunset sky rather than during the middle of the night. The tail of the comet, composed of gas and dust reflecting sunlight, is often the most striking feature.
It's worth noting that Halley's Comet was last visible from Earth in 1986, so we won't see it again until around the year 2061. Future appearances of Halley's Comet can be predicted based on its orbital parameters, and astronomers can provide more precise information about its visibility closer to the time of its next approach.